This article delves into the implementation details of the high-performance LRU cache in LevelDB, covering its cache interface design, the LRUHandle data structure, doubly linked list optimizations, and sharding mechanism. By analyzing core designs like clever reference counting management, the dummy node technique, and lock sharding to reduce contention, it showcases the optimization strategies for an industrial-grade cache system. Combining code and diagrams, the article helps readers understand how LevelDB achieves a high-concurrency, high-performance cache and how these design techniques can be applied in their own projects.